Fuels for internal combustion engines



Patented Feb. 25, 1936 2,032,242 FUELS FOR mnng l COBIBUSTION ENG Samuel Whyte, Redhill, England No Drawing. Application January 11, 1934, Serial No. 706.295. 1933 a '7 Claims.

This invention relates to improvements in fuels for internal combustion engines.

It is well known that there is a tendency for a carbonaceous deposit to form on the inside surface of thecombustion chambers of internal combustion engines. This deposit is formed by the partial combustion of the fuel and by the partial oxidation of and the effects of heat on the oil used for lubrication of the mechanism. This deposit has a low thermal conductivity compared with the metal of the combustion chamber with the result that the temperature of its surface tends to rise and ultimately, when the deposit becomes of appreciable thickness, reaches such a level that pre-ignition of the charge occurs when the engine is under load with consequent loss of power and damage to the mechanism. The deposit mayalso form on the insulators of the sparking plugs and interfere with their operation.

This deposit of carbonaceous material increases during the running of the engine and it is customary at intervals to dismantle the engine and remove the deposit.

The carbonaceous .depositrconsists largely of carbon but this is bound and rendered strongly adhesive to the walls of the combustion chamber by an admixture of oxidized oil and other tarry, asphaltic or resinous matter derived partially from the fuel but mainly from the lubricating oil;

The object of this invention is to provide a fuel which will inhibit the accumulation of carbonaceous deposits in the combustion chamber or alternatively will remove such deposits if already formed therein.

A further object of this invention is to increase the emciency of internal combustion engines by providing a fuel which will prevent the formation of carbonaceous deposits in the combustion chamber; and other objects will be made apparent hereinafter.

It has been found that the tarry, asphaltic, resinous or oxidized matter constituting the binding and'adhesive agent in the carbonaceous layer which ordinarily forms as above is characterized in that it is not softened or dissolved by any of the constituents normally occurring I in petroleum fuels or the like or .in lubricating oils; and this invention accordingly consists in providing a fuel which contains or is associated with a proportion of a substance or substances which are capable of softening and/or dissolving the binding and adhesive constituents .in the In Great Britain January 17,

carbonaceous deposit; such substances being hereinafter referred to as solvents.

A considerable range of suitable solvents is known but I have found that it is preferable to use compounds having boiling points between 5 100 C. and 200 C. though I do not limit myself to this range of boiling points. It is also advisable to avoid the use of solvents containing nitrogen, halogens or sulphur or any other chememploy solvents having boiling points substantially above that of the fuel but it is inadvisable to employ solvents haying boiling points above 200 C. since there is then a tendency for the solvent to condense before the fuel charge enters the combustion chamber and be deposited in the induction pipe of the engine.

Solvents which I prefer to use are complex alcohols, ketones, saturated cyclic compounds or other oxygen containing bodies which are highly active in attacking and softening oxidized oils, 3 tarry, asphaltic or resinous bodies but I do not limit myself to solvents in any or all of these classes.

Examples of suitable solvents are:-Cyclohexanol, methyl cyclohexanol, cyclohexanone, methyl-cyclohexanone, diacetone alcohol, mesityl oxide, eucalyptus 011. This list of solvents is not intended to be definitive but only to illustrate the range of classes of compounds from which suitable solvents may be obtained. 40

I have found that an engine which has already developed a heavy layer ofcarbonaceous material may be decarbonized by running for some hours on a fuel consisting of commercial petrol or -benzol mixture to which has been added a small quantity of solvent as herein defined, for instance, about 1 per cent. of cyclohexanone.

The above is one application of my invention which I claim but I prefer to start with an engine substantially free from carbonaceous deposits and use a fuel improved in the sense indicated and consisting say of commercial petrol or benzol mixture to which has been added a smaller proportion of one'of the solvents indicated, for instance about 0.1 per cent. of cyclohexanone. I

' have found that such procedure effectively prevents the formation of carbonaceous layers.

It must beunderstood that there is no objection to the use of substantially larger proportions of solvents but since the cost of these is generally higher than that of the fuel it is desirable to use the minimum effective quantities; and the order of these latter has been indicated in the above examples.

It must also be understood that I do not limit myself to the use of a single solvent of the kind referred to, since mixtures of such solvents may be equally well employed.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is v 1. As a fuel for internal combustion engines, a mixture of-a conventional liquid fuel therefor with not substantially exceeding one percent of a monocyclic ketone having a boiling point within the approximate range of 100 C. to 200 C.

2. As a fuel for internal combustion engines a mixture of conventional fuel therefor with at least one of the group of ketones consisting of cyclohexanone and, methyl cyclohexanone, in the approximal maximum of one percent.

3. As a fuel for internal combustion engines a mixture of a liquid fuel of the benzol-gasoline type therefor and about 1 percent of cyclohexanone.

4. As a decarbonating and resinous deposit inhibiting composition for use in an internal combustion engine a mixture of a conventional liquid fuel therefor and up to 1 percent of cyclohexanone.

5. A motor fuel of the type normally tending to deposit carbon and gummy substances in the motor to which is added a small quantity of a monocyclic ketone of boiling point ranging between 100 to 200 C. in the order of one percent. 6. A motor fuel of the type normally tending to deposit carbon and gummy substances in the motor to which is added'approximately one percent of a. monoallcyclic ketone.

7. A method preventing the formation of gummy and carbonaceous deposits in the cylinders of internal combustion engines comprising adding, to the motor fuel approximately 1 percent of a monocyclic ketone boiling in the range of 100 to 200 C.

' SAMUEL WHYTE. 

